On Oct. 4th, 1957, at 10:29 PM Moscow time, the Soviet Union successfully launched Sputnik 1 into space on a repurposed R-7 rocket. The world’s first artificial satellite, Sputnik was about 22 inches (58 centimeters) in diameter and weighed 184 pounds (84 kilograms). Although there were no scientific instruments aboard, the transmitter it carried sentContinue reading "Oct. 4th, 1957: Sputnik launches"

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Looking for a sky event this week? Check out our full Sky This Week column.  October 3: Dione transits Saturn We’re back at Saturn this evening with the planet as the main attraction as the ringed world reaches opposition today at 8 A.M. EDT. Rising around sunset and setting around sunrise, it is visible all night inContinue reading "The Sky Today on Sunday, October 4: Saturn reaches opposition"

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A 12-ton rocket loaded with a 1-ton warhead, the V-2’s successful launch would prove to be exceptionally significant to both the military and to space exploration. On Oct. 3, 1942, the V-2 was fired from Peenemunde, Germany – its fourth test, and the first to succeed. The rocket rose to an altitude of 60 milesContinue reading "Oct. 3, 1942: The V-2 successfully launches"

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Huang Dandan, taken from Shennongjia, Hubei, China The gegenschein, a faint glow of sunlight scattered back toward Earth by dust grains in the inner solar system, sits in Aquarius at the point directly opposite the Sun in this all-sky view. The Milky Way arcs across the center, and the red light at bottom is aContinue reading "Gegenschein over Shennongjia"

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Looking for a sky event this week? Check out our full Sky This Week column.  October 2: Venus stands still The small moon Dione transits Saturn starting just before midnight EDT. Tenth-magnitude Dione crosses the far northern region of the planet, beginning its journey just minutes after 11:40 P.M. EDT and taking about an hour and aContinue reading "The Sky Today on Saturday, October 3: Dione transits Saturn"

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If a train leaves the station in Exeter, England, headed south toward Newton Abbot five years before the railway line opens, how long until anyone figures out that it didn’t happen? Well, evidently about 155 years. A report on magnetic storms, published in Nature in 1871, described an incident thought to be the earliest recordedContinue reading "Case closed on long-standing space weather mystery"

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What type of lighting emits the least amount of light pollution? Peter BladoTacoma, Washington First, use a good lighting fixture, one that is a “full cutoff.” That means there is no direct upgoing light at all. It generally also means there is very little light just below the horizontal, which is the kind of lightContinue reading "How can I reduce my personal contribution to light pollution?"

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An ancient solar eclipse changed the course of a military conflict when it cast a shadow on a battle over Corinth between the Spartans, commanded by Cleombrotus, and the invading Persians, led by Xerxes I. Herodotus wrote that, “while [Cleombrotus] was offering sacrifice to know if he should march out against the Persians, the SunContinue reading "Oct. 2, 480 B.C.E.: A eclipse causes a retreat"

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Looking for a sky event this week? Check out our full Sky This Week column.  October 1: Perseus’ Double Cluster The brilliant planet Venus stands stationary against the background stars of Virgo at 10 A.M. EDT.  Together with Mercury, Venus is visible for a short time in the western sky after sunset, but you’ll want a clearContinue reading "The Sky Today on Friday, October 2: Venus stands still"

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